Rev. A.4, 12/01
Page- 11
distance between the magnet and strike plate to the point where locking may become
problematical.
2.5 MOUNTING ON MOTORIZED BI-PARTING DOORS
Such doors are commonly found on the perimeters of large retail stores such as supermarkets.
Two doors
electrically slide open
to admit a customer. They are typically activated by a
motion detector or mat. These same doors however
must allow emergency egress
in the
event of a fire and the motor or wiring may be damaged in a fire, so some mechanical means
must be present to permit this emergency egress. This is accomplished by the doors
possessing a “
breakaway
” feature. When they are pushed from the inside with moderate force,
they swing outward permitting egress.
Naturally the doors must be locked when the store is not in operation or it would be trivially easy
for a thief to enter by pulling the breakaway feature open. This is conventionally done by using
a key and mechanical lock but it may be electrically accomplished by using the SAM or SAM2.
In this way, all doors can be automatically locked and unlocked as the store closes and opens
without the need for a guard to carry a key to each door. The SAM is able to perform this
function because it operates bi-directionally. The strike can slide into locking position or swing
into locking position. The physical mounting techniques for this application are the same as on
the equivalent hollow aluminum door (see preceding Sections).
3. ELECTRICAL INSTALLATION
3.1 GENERAL ELECTRICAL CHARACTERISTICS
SAM’s constitute a low current electric load. Due to internal circuitry, they do not show the
normal characteristics of an electromagnetic or other inductive load. Inductive kickback is
suppressed, so arcing across switch contacts need not be a concern. This suppression also
protects nearby access control or computer equipment from possible interference. Electrically
speaking, the load is nearly purely resistive in nature.
3.2 STANDARD LOCK
For operation, DC voltage (12 or 24VDC), must be provided to the lock. The
SAM will accept
either voltage
and will automatically adjust its current draw to maintain the correct power
consumption (4 watts). This is
350 mA at 12 Volts or 175 mA at 24 Volts
.
The SAM2 is
supplied in separate versions for 12 and 24 volt operation. The SAM2-12 draws 125 mA
and the SAM2-24 draws 62 mA.
For either model, the red wire re12VDC or +24VDC,
and the black wire, 0V (negative).
If the lock is connected with reverse polarity, it will not
function at all.
The voltage source may be regulated, filtered or pulsating DC (trans
bridge rectifier).
Half wave pulsating DC generated by a transformer and single diode will
not properly operate the SAM’s.
An exact voltage level is not necessary. Less than standard
voltage will somewhat reduce holding force but will cause no harm. Overvoltage up to 30% is
acceptable.
It is good practice to use power supplies with 1/3 extra capacity beyond the current
requirements of the load. This greatly reduces the possibility of heat induced power supply
failure and also allows for future expansion. Power supply cost is a small fraction of the job cost
and should not be skimped on.
Switches may be wired as necessary between the lock and power source. Internal circuitry
eliminates inductive kickback, so neither electromechanical switches nor solid state devices will
be damaged by arcing when the unit is shut off.